Shield case, manufacturing method therefor, and electronic device

ABSTRACT

An electronic device includes a circuit board on which an electronic component is mounted and a ground pattern surrounding the electronic component is formed, a shield case which is formed by drawing a mesh material formed by weaving a conductive wire, stores the electronic component, and has a box-like room with a peripheral portion for ground around an open end, and a housing which incorporates the circuit board and shield case and has a rib formed at a predetermined position on the inner surface in order to bring the peripheral portion into press contact with the ground pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Applications No. 2000-388160, filed Dec.21, 2000; and No. 2001-378673, filed Dec. 12, 2001, the entire contentsof both of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a shield case for preventingradio interference between elements and circuits of an electronicdevice, radio incidence on the device, and radio emission from thedevice, a method of manufacturing the shield case, and an electronicdevice in which the shield case is mounted.

[0004] 2. Description of the Related Art

[0005] In general, an RF (radio frequency) electronic device such as aportable telephone is provided with an RF shield in order to mainlyprevent radio interference between modules and external radio emission.FIG. 1 shows an example of an RF shield. A shield case 6 is attached toa circuit board 2 so as to cover an electronic component 4 in order toshield the electronic component 4 mounted on the circuit board 2 from RFwaves. The shield case 6 comprises a top plate 8 and four side plates10, and has a box-like outer appearance with an open surface (bottomsurface). The material of the shield case 6 is a resin material or metalplate (metal).

[0006]FIG. 2 shows the cross section of a shield case 6A made of a resinmaterial. The surfaces of the top plate 8 and side plates 10 of theshield case 6A are coated with a plating layer 12 made of a conductivemetal. A ground pattern 16 surrounding the electronic component 4 isformed on the surface of a base 14 of the circuit board 2 which supportsthe electronic component 4. When the shield case 6A is mounted at apredetermined position of the circuit board 2 so as to cover theelectronic component 4, the plating layer 12 at the open edges of theside plates 10 of the shield case 6A contacts the ground pattern 16. Inthis manner, the shield case 6A is rendered conductive to shield theelectronic component 4 from RF waves.

[0007] However, if the shield case 6A is made from a resin material, agap may be formed between the ground pattern 16 of the circuit board 2and the plating layer 12 at the open edges of the side plates 10 of theshield case 6A due to deformation (distortion) of the shield case 6A ordeformation (corrugation) of the circuit board 2. In this case, theplating layer 12 and ground pattern 16 cannot be in satisfactory contactwith each other, and desired shielding performance cannot bemanufactured, degrading radio performance.

[0008] To prevent this, when the shield case 6A is made from a resinmaterial, an conductive elastic member 18 such as a conductive rubber orconductive spring with both elasticity and conductivity is applied tothe open ends of the side plates 10 of the shield case 6A, as shown inFIG. 3. The conductive elastic member 18 can achieve secure contactbetween the ground pattern 16 of the circuit board 2 and the platinglayer 12 at the open edges of the side plates 10 of the shield case 6Aeven upon deformation of the shield case 6A or circuit board 2.

[0009] In the above arrangement, however, the conductive elastic member18 such as a conductive rubber or conductive spring must be aligned tothe open edge of the shield case 6A in mounting the shield case 6A onthe circuit board 2. This complicates the mounting process of the shieldcase 6A. Since the resin material is plated with the conductivematerial, the plating layer is difficult to remove from the resinmaterial in disposal, which makes recycling difficult.

[0010]FIG. 4 shows the cross section of a shield case 6B made of a metalplate. The open edges of the side plates 10 of the shield case 6B areattached to the ground pattern 16 of the circuit board 2 via solder 20.

[0011] The solder 20 can achieve secure contact between the open edgesand the ground pattern 16 even upon deformation of the shield case 6B orcircuit board 2. In this case, however, the metal plate shield case 6Bis difficult to dismount from the circuit board 2 in disposal, whichalso makes recycling difficult. The box-like case is manufactured byprocessing a flat metal plate (pressing), so a shield case of acomplicated shape cannot be pressed.

[0012] A conventional shield case made of a resin material suffers thefollowing problem. That is, a gap is formed between the ground patternof the circuit board and the plating layer at the open edges of the sideplates of the shield case owing to deformation of the shield case orboard. At the gap portion, the ground pattern and plating layer cannotsatisfactorily contact each other. Desired shielding performance cannotbe manufactured, degrading radio performance. A solution to this problemmay complicate the mounting process of the shield case, as shown in FIG.2.

[0013] In a shield case made from a metal plate, soldering achievessecure contact between the open edges of the side plates of the metalplate shield case and the ground pattern of the circuit board. However,the shield case is difficult to dismount from the circuit board. Since aflat metal plate is processed, a case of a complicated shape cannot bepressed. Further, either a resin material or metal plate used as theshield case material makes recycling difficult.

BRIEF SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to provide a shield casewhich is easily mounted/dismounted, obtains desired shieldingperformance, and is easily manufactured, a method of manufacturing theshield case, and an electronic device in which the shield case ismounted.

[0015] According to an embodiment of the present invention, a shieldcase is made from a mesh material formed by weaving a conductive wire,has a box-like shape with an open surface, and has a peripheral portionfor ground at an open end of the box.

[0016] A shield case according to another embodiment is made from a meshmaterial formed by weaving a conductive wire, has a plurality ofbox-like rooms each with an open surface, and has a peripheral portionfor ground at an open end of each box.

[0017] The shield case according to the above embodiments is elasticbecause the mesh material is used. The shield case is therefore reliablygrounded without using any elastic member or solder, unlike the priorart.

[0018] In the shield case according to a still another embodiment, anend of the conductive wire of the mesh material is rounded. Thus, theshield case need not be carefully handled by hands or the like.

[0019] In the shield case according to a still further embodiment, amesh of the conductive wire of the mesh material crosses a fold of thebox. A mesh of the conductive wire of the mesh material preferablycrosses a fold of the box at 45°. Not only the conductive wire stretchesin forming into a box shape, but also the mesh shape is widened. Hence,the conductive wire is not cut.

[0020] According to still another embodiment, there is provided a shieldcase manufacturing method of drawing a mesh material formed by weaving aconductive wire, forming a box-like room with an open surface, andforming a peripheral portion for ground at an open end of the box.

[0021] According to still further embodiment, there is provided a shieldcase manufacturing method of interposing a mesh material formed byweaving a conductive wire between convex and concave molds to draw themesh material, forming a plurality of box-like rooms each with an opensurface, and forming a peripheral portion for ground at an open end ofeach box.

[0022] Since the shield case manufacturing method according to the stillanother embodiment and still further embodiment uses the mesh material,a case of an arbitrary shape is easily manufactured.

[0023] An electronic device according to still another embodimentcomprises a circuit board on which an electronic component is mountedand a ground pattern surrounding the electronic component is formed, ashield case which has a room for storing the electronic component, has aperipheral portion formed around an open surface of the room, and ismade from a mesh material formed by weaving a conductive wire, and ahousing which incorporates the circuit board and the shield case and hasa projection formed at a predetermined position on an inner surface inorder to bring the peripheral portion into press contact with the groundpattern.

[0024] In the electronic device according to the still anotherembodiment, the shield case is reliably brought into contact with theground pattern of the circuit board without using any elastic member orsolder. The shield case is easily be mounted/dismounted.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0025] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate embodiments of thepresent invention and, together with the general description given aboveand the detailed description of the embodiments given below, serve toexplain the principles of the present invention in which:

[0026]FIG. 1 is a perspective view showing a conventional shield casetogether with a circuit board;

[0027]FIG. 2 is a sectional view showing an example of a state wherein aconventional shield case using a resin material is mounted on thecircuit board;

[0028]FIG. 3 is a sectional view showing another example of the statewherein the conventional shield case using a resin material is mountedon the circuit board;

[0029]FIG. 4 is a sectional view showing an example of a state wherein aconventional shield case using a metal plate is mounted on a circuitboard;

[0030]FIG. 5 is a perspective view showing the arrangement of a shieldcase according to an embodiment of the present invention;

[0031]FIG. 6 is a plan view showing the shield case according to theembodiment of the present invention;

[0032]FIGS. 7A and 7B are views for explaining a method of fabricatingthe shield case according to the embodiment of the present invention bydrawing;

[0033]FIG. 8 is a perspective view for explaining thermal cutting of anunnecessary end by a laser in fabricating the shield case according tothe embodiment of the present invention;

[0034]FIG. 9A is a view showing the cut portion of a wire in the shieldcase by pressing;

[0035]FIG. 9B is a view showing the cut portion of a wire in the shieldcase according to the embodiment of the present invention;

[0036]FIGS. 10A, 10B, and 10C are views for explaining the effect offorming while tilting the weaving direction of a mesh material from thedrawing direction in the shield case according to the embodiment of thepresent invention;

[0037]FIG. 11 is an exploded perspective view showing the structure of aportable telephone which incorporates the shield case according to theembodiment of the present invention; and

[0038]FIG. 12 is a sectional view showing the detailed structure of themajor portion of the portable telephone shown in FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

[0039] An embodiment of a shield case according to the present inventionwill now be described with reference to the accompanying drawings.

[0040]FIG. 5 is a perspective view showing the outer appearance of ashield case according to the embodiment of the present invention. FIG. 6is a plan view of the shield case. A shield case 30 is divided intorooms for respective electronic components which must be shielded. Inthis embodiment, the shield case 30 has three rooms 32 a, 32 b, and 32c. The rooms 32 a, 32 b, and 32 c have top plates 34 a, 34 b, and 34 c,and side plates 36 a, 36 b, and 36 c, respectively. A peripheral portion38 is formed around the open edges of the side plates 36 a, 36 b, and 36c of the rooms 32 a, 32 b, and 32 c.

[0041] The material of the shield case 30 is not a metal plate but aconductive wire such as a mesh material formed by weaving a steel wire.The mesh material can attain a satisfactory shield effect as far as themesh size is {fraction (1/100)} or less of the wavelength. The shieldcase 30 is manufactured by drawing the mesh material.

[0042]FIGS. 7A and 7B are views for explaining a method of fabricatingthe shield case 30 by drawing. As shown in FIG. 7A, a punch 42 and die44 corresponding to the shapes of the rooms 32 a, 32 b, and 32 c of theshield case 30 are prepared. A flat mesh material 46 is interposedbetween the punch 42 and die 44, drawn several times under a pressure P,and removed from the punch 42 and die 44. The shield case 30 ismanufactured from the mesh material 46 deformed as shown in FIG. 7B.

[0043] The mesh material 46 is larger than the shield case, and anunnecessary end (broken line in FIG. 8) is cut off after drawing. In ashield case manufactured by pressing of a metal plate described in theprior art, the end is cut off by pressing. If the same cutting is donefor the shield case of this embodiment, the cut portion becomes sharp,as shown in FIG. 9A, because the wires of the mesh material areextracted one by one. Such a shield case is difficult to manuallyhandle. To prevent this, an unnecessary end is thermally cut by a laserin the embodiment. In this case, the end of the mesh wire can berounded, as shown in FIG. 9B. The shield case need not be carefullyhandled by hands or the like.

[0044] Since the material stretches by drawing, a metal plate may beworn out at a drawn portion if it is used as the material. To thecontrary, a mesh material resistant to drawing is hardly worn out. Thestrength of the mesh material is increased by devising the mesh layout.Drawing is performed by laying out the mesh material such that theweaving direction of the mesh material, i.e., the direction of a steelwire is tilted by 45° from each side of a rectangle forming the outershape of the rectangular top plate 34 a, 34 b, or 34 c, as shown inFIGS. 5 and 6. FIGS. 10A, 10B, and 10C are views for explaining theeffect of laying out the mesh material in this direction and drawing it.When the steel wire direction is set parallel to each side of therectangle forming the outer shape of the top plate 34 a, 34 b, or 34 c,the steel wire direction coincides at a drawn portion with the directionof each side of the rectangle forming the outer shape of the top plate34 a, 34 b, or 34 c, as shown in FIG. 10A. Thus, drawing is done mainlyby stretch of the steel wire, and the steel wire may be cut by drawing.To prevent this, the steel wire direction is tilted by 45° from eachside of the rectangle forming the outer shape of the top plate 34 a, 34b, or 34 c, and drawing is performed in a direction tilted by 45° fromthe steel wire direction, as shown in FIG. 10B. Hence, not only thesteel wire stretches, but also the mesh shape is widened, as shown inFIG. 10C. The shape as shown in FIG. 5 can be realized without cuttingthe steel wire. The tilt angle of the steel wire from each side of therectangle forming the outer shape of the top plate 34 a, 34 b, or 34 cis not limited to 45°. By tilting the steel wire direction by anotherarbitrary angle, the mesh shape can be widened to a certain degree.

[0045] In this way, the shield case 30 is manufactured using a meshmaterial by drawing. Compared to pressing a metal plate, a shield caseof a complicated shape can easily be formed. The peripheral portion 38can be made elastic by using a mesh material formed by weaving a steelwire as the material of the shield case 30. The shield case 30 can bereliably brought into contact with the ground pattern of the circuitboard without attaching the shield case to the circuit board via anotherconductive elastic member, unlike the use of a resin material describedin the prior art. The shield case 30 can easily be mounted.

[0046] Further, the shield case 30 can easily be dismounted because itneed not be soldered, unlike the use of a metal plate described in theprior art. Since the shield case 30 is easily dismounted and made of asingle material, it can easily be recycled.

[0047] In addition, the shield case becomes lighter than a shield casemade from a flat plate by using the mesh material formed by weaving asteel wire as the material of the shield case 30. Note that the materialof the shield case 30 is not limited to the mesh material formed byweaving a steel wire, but can be a mesh material formed by weavinganother conductive wire, e.g., a wire of copper, nickel, or aluminum.

[0048]FIGS. 11 and 12 show the structure of a portable telephone inwhich the shield case according to the embodiment of the presentinvention is assembled. FIG. 11 is an exploded perspective view showingthe portable telephone, and FIG. 12 is a sectional view showing thedetailed structure of the main part. As shown in FIG. 11, the portabletelephone comprises upper and lower cases (housings) 52 and 54 made of aplastic, a circuit board 58 which is stored in the upper and lower cases(housings) 52 and 54 and supports electronic components 56 a and 56 b,and a shield case 60.

[0049] As shown in FIGS. 11 and 12, the surface of a base 62 of thecircuit board 58 bears a wiring pattern (not shown) which connects themounted electronic components 56 a and 56 b, and bears a ground pattern64 surrounding the electronic components 56 a and 56 b.

[0050] As shown in FIG. 12, the shield case 60 has rooms 60 a and 60 bfor incorporating the electronic components 56 a and 56 b. A peripheralportion 66 is formed around the open surfaces of the rooms 60 a and 60b. Ribs (projections) 68 for pressing the peripheral portion 66 areformed on the lower case 54 at positions corresponding to the peripheralportion 66 formed around the open surfaces of the rooms 60 a and 60 b ofthe shield case 60. The shield case 60 is so mounted as to cover theelectronic components 56 a and 56 b on the circuit board 58. The shieldcase 60 is brought into contact with the ground pattern 64 of thecircuit board 58 by pressing the peripheral portion 66 of the shieldcase 60 by the ribs (projections) 68 of the lower case 54. Thisstructure can attain secure contact between the shield case 60 and theground pattern 64 of the circuit board 58 and can realize RF shielding.

[0051] The ground pattern 64 formed on the circuit board 58 need notalways be formed at all positions where the ground pattern 64 surroundsthe mounted electronic components 56 a and 56 b. A ground patternbetween adjacent electronic components may be properly omitted as far asthe ground pattern is formed on at least the outermost position wherethe ground pattern surrounds all the electronic components 56 a and 56b.

[0052] As has been described above, according to the embodiment, a meshmaterial formed by weaving a conductive wire is adopted as the materialof a shield case assembled into an electronic device. The shield casebecomes lighter than a shield case made from a flat plate. The shieldcase can easily be mounted/dismounted on/from the circuit board, and caneasily be recycled.

[0053] While the description above refers to particular embodiments ofthe present invention, it will be understood that many modifications maybe made without departing from the spirit thereof. The accompanyingclaims are intended to cover such modifications as would fall within thetrue scope and spirit of the present invention. The presently disclosedembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims, rather than the foregoing description,and all changes that come within the meaning and range of equivalency ofthe claims are therefore intended to be embraced therein. For example, ashield case made up of a plurality of rooms has been exemplified in theabove description, but the shield case may be comprised of only a room.A portable telephone has been exemplified as an electronic device, butthe electronic device is not limited to this as far as it requires RFshielding.

What is claimed is:
 1. A shield case comprises: a mesh material formedby weaving a conductive wire and having a box-like shape portion with anopen surface; and a peripheral portion for ground provided at an openend of the box-like portion.
 2. The shield case according to claim 1,wherein said mesh material has a plurality of box-like rooms each withan open surface, and the peripheral portion for ground is formed at anopen end of each box.
 3. The shield case according to claim 1, whereinan end of the conductive wire of the mesh material is rounded.
 4. Theshield case according to claim 1, wherein the box-like shape portion ismanufactured by drawing the mesh material.
 5. The shield case accordingto claim 1, wherein a mesh of the conductive wire of the mesh materialcrosses a fold of the box-like portion.
 6. A shield case manufacturingmethod comprising: drawing a mesh material formed by weaving aconductive wire; forming a box-like room with an open surface; andforming a peripheral portion for ground at an open end of the box-likeroom.
 7. The shield case manufacturing method according to claim 6,wherein drawing the mesh material comprises interposing the meshmaterial between convex and concave molds, forming the box-like roomcomprises forming a plurality of box-like rooms each with an opensurface, and forming the peripheral portion comprises forming theperipheral portion at an open end of each box.
 8. The method accordingto claim 6, further comprising thermally cutting an end of theconductive wire of the mesh material by laser after drawing.
 9. Themethod according to claim 6, wherein drawing the mesh material comprisesdrawing the mesh material so as to make a mesh of the conductive wirecross a fold of the box-like room.
 10. An electronic device comprising:a board on which an electronic component is mounted and a ground patternsurrounding the electronic component is formed; a shield case includinga box-like room for storing the electronic component and a peripheralportion formed around an open surface of the room, the shield case beingmade from a mesh material formed by weaving a conductive wire; and ahousing which incorporates said board and said shield case and has aprojection formed at a predetermined position on an inner surface inorder to bring the peripheral portion into press contact with the groundpattern.
 11. The electronic device according to claim 10, wherein an endof the conductive wire of the mesh material is rounded.
 12. Theelectronic device according to claim 10, wherein the box-like room ofthe shield case is manufactured by drawing the mesh material.
 13. Theelectronic device according to claim 10, wherein a mesh of theconductive wire of the mesh material crosses a fold of the box-likeroom.